Public Sub UnMerge() 

public void UnMerge()

private void btnSpread_Click(object sender, System.EventArgs e)
{
    //Dimension a Workbook and add a sheet to its Sheets collection
    GrapeCity.SpreadBuilder.Workbook sb = new GrapeCity.SpreadBuilder.Workbook();
    sb.Sheets.AddNew();
    //Set up properties and values for columns, rows and cells as desired
    sb.Sheets[0].Name = "Customer Call List";
    sb.Sheets[0].Columns(0).Width = 2 * 1440;
    sb.Sheets[0].Columns(1).Width = 1440;
    sb.Sheets[0].Columns(2).Width = 1440;
    sb.Sheets[0].Rows(0).Height = 1440/4;
    //Header row
    sb.Sheets[0].Cell(0,0).SetValue("Company Name");
    sb.Sheets[0].Cell(0,0).FontBold = true;
    sb.Sheets[0].Cell(0, 0).Merge(0, 1);
    sb.Sheets[0].Cell(0,1).SetValue("Contact Name");
    sb.Sheets[0].Cell(0,1).FontBold = true;
    sb.Sheets[0].Cell(0,2).SetValue("Phone");
    sb.Sheets[0].Cell(0,2).FontBold = true;
    //First row of data
    sb.Sheets[0].Cell(1,0).SetValue("GrapeCity");
    sb.Sheets[0].Cell(1,1).SetValue("Mortimer");
    sb.Sheets[0].Cell(1,2).SetValue("(614) 895-3142");
    if (sb.Sheets[0].IsMerged(0, 0))
    {
        sb.Sheets[0].Cell(0, 0).UnMerge();
    }
    //Save the Workbook to an Excel file
    sb.Save (Application.StartupPath + @"\x.xls");
    MessageBox.Show("Your Spreadsheet, " + sb.Sheets[0].Columns(0).OwnerSheet.Name + ", has been saved to " + Application.StartupPath + "\\x.xls");
    sb.Sheets[0].Clear();
}

Private Sub btnSpread_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSpread.Click
    'Dimension a Workbook and add a sheet to its Sheets collection
    Dim sb As New GrapeCity.SpreadBuilder.Workbook
    sb.Sheets.AddNew()
        
    'Set up properties and values for columns, rows and cells as desired
    With sb.Sheets(0)
        .Name = "Customer Call List"
        .Columns(0).Width = 2 * 1440
        .Columns(1).Width = 1440
        .Columns(2).Width = 1440
        .Rows(0).Height = 1440 / 4
        'Header row
        .Cell(0, 0).SetValue("Company Name")
        .Cell(0, 0).FontBold = True
        .Cell(0, 0).Merge(0, 1)
        .Cell(0, 1).SetValue("Contact Name")
        .Cell(0, 1).FontBold = True
        .Cell(0, 2).SetValue("Phone")
        .Cell(0, 2).FontBold = True
        'First row of data
        .Cell(1, 0).SetValue("GrapeCity")
        .Cell(1, 1).SetValue("Mortimer")
        .Cell(1, 2).SetValue("(614) 895-3142")
     End With
    If sb.Sheets(0).IsMerged(0, 0) Then
        sb.Sheets(0).Cell(0, 0).UnMerge()
    End If
    'Save the Workbook to an Excel file
    sb.Save(Application.StartupPath & "\x.xls")
    MsgBox("Your Spreadsheet, " & sb.Sheets(0).Columns(0).OwnerSheet.Name & ", has been saved to " & Application.StartupPath & "\x.xls")
    sb.Sheets(0).Clear()
End Sub